1. Technical Field
This disclosure relates generally to a writer used in perpendicular magnetic recording (PMR) and particularly to the design of shields that improve their performance.
2. Description
Current Perpendicular Magnetic Recording (PMR) writer designs typically employ a main pole surrounded by fully wrapped around shields, i.e., two symmetric laterally disposed side shields sandwiched above and below by a trailing shield (above) and leading shield (below). This configuration is designed and fabricated to improve both the field gradients in the down track and cross track directions as well as to improve the ATE (adjacent track erasure) performance. The prior art teaches several different shield designs to accomplish various types of improved writer performance. Examples are taught in Jiang et al. (U.S. Pat. No. 8,068,312), Yu et al. (U.S. Pat. No. 8,582,241) and Hsu et al. (U.S. Pat. No. 7,009,812).
FIG. 1 schematically shows the ABS (air bearing surface) of a rather typical prior art PMR writer with fully wrapped around shields. The components of this design include the write pole (10), two laterally disposed, mirror symmetric side shields (20), a trailing shield (30) “above” the pole and a leading shield (40) “below” the pole. Here “leading” refers to the direction into which a rotating recording medium moves relative to the ABS of the writer. The pole is separated from the shields by various gaps, typically filled with non-magnetic material. The gaps are denoted side gaps (25), leading edge gap (45) and write gap (35).